Abstract: A viscous fluid shear clutch comprises a two-part outer casing 14,15 and an inner clutch member 10 between which is defined a clearance gap into which viscous fluid may flow to provide an adjustable degree of coupling between the casing and the clutch members. Fluid is continually pumped out of the gap by a circumferential scoop pummp. The clutch may be assembled for reverse operation by indexing the casing parts relative to one another. The quantity of fluid in the gap may be controlled dependent on sensed temperature and sensed speed or sensed temperature alone. A thermo pressure valve provides a pressure force related to the sensed temperature; this relationship may be inverse for failsafe operation.

Abstract: A viscous fluid shear clutch comprises a two-part outer casing 14,15 and an inner clutch member 10 between which is defined a clearance gap into which viscous fluid may flow to provide an adjustable degree of coupling between the casing and the clutch members. Fluid is continually pumped out of the gap by a circumferential scoop pump. The clutch may be assembled for reverse operation by indexing the casing parts relative to one another. The quantity of fluid in the gap may be controlled dependent on sensed temperature and sensed speed or sensed temperature alone. A thermo pressure valve provides a pressure force related to the sensed temperature; this relationship may be inverse for failsafe operation.

Abstract: A viscous fluid shear clutch comprises a two-part outer casing 14,15 and an inner clutch member 10 between which is defined a clearance gap into which viscous fluid may flow to provide an adjustable degree of coupling between the casing and the clutch members. Fluid is continually pumped out of the gap by a circumferential scoop pump. The clutch may be assembled for reverse operation by indexing the casing parts relative to one another. The quantity of fluid in the gap may be controlled dependent on sensed temperature and sensed speed or sensed temperature alone. A thermo pressure valve provides a pressure force related to the sensed temperature; this relationship may be inverse for failsafe operation.

Abstract: A viscous fluid shear clutch comprises a two-part outer casing 14,15 and an inner clutch member 10 between which is defined a clearance gap into which viscous fluid may flow to provide an adjustable degree of coupling between the casing and the clutch members. Fluid is continually pumped out of the gap by a circumferential scoop pump. The clutch may be assembled for reverse operation by indexing the casing parts relative to one another. The quantity of fluid in the gap may be controlled dependent on sensed temperature and sensed speed or sensed temperature alone. A thermo pressure valve provides a pressure force related to the sensed temperature; this relationship may be inverse for failsafe operation.

Abstract: The invention relates to a viscous fluid variable drive to a rotary cooling fan for an engine, the drive being automatically controlled in response to sensed parameters such as temperature. In one example the drive unit includes an inner drive member 14 within a casing 10, 11 which includes a pump 24 continuously delivering fluid from the gap to a central valve port 25 when the fluid returns to a reservoir 20 and then spills through an aperture 26 back into the clearance gap. The valve port 25 in the supply passage from the pump is automatically controlled by a valve 30 actuated by compressed air in a line 36 from a remote thermal sensing unit. In another embodiment the valve 30 is controlled by a bi-metal strip 46 sensitive to ambient air. The pressure from the pump may also be used to actuate a servo valve 61 controlling tbe return flow of fluid from the reservoir 20 to the clearance gap. The valve may be in two separate units controlled spearately by valve elements 101 and 30'".

Abstract: A viscous fluid clutch for driving a cooling fan 18 from the crankshaft of an internal combustion engine includes an outer rotary casing 11, 12 connected to the fan and an inner rotary member 10 connected to the crankshaft coupling 9. The clearance gap between these two members is normally occupied by a viscous fluid and the drive is automatically adjusted by varying the quantity of fluid in the gap. A scoop pump 22 continuously pumps fluid from the gap inwards along passage 24 to a reservoir 20 via control valve 50, and the fluid returns to the clearance gap from the reservoir via a port 26. The valve 50 includes a piston 61, which is subject on one side of the pressure of the fluid supplied by the scoop pump 22, and hence to the relative speed of rotation between the crankshaft and the fan. In the other direction the piston 61 is subject to the fluid servo pressure in a conduit 48 derived from the sensed temperature of the engine coolant in duct 40.

Abstract: A viscous fluid transmission including a rotary casing adapted to receve a viscous fluid and a rotary element within the casing. The casing and the rotary element are connected respectively to two drive shafts. Means is provided for pumping the fluid from its normal position in the casing into a holding reservoir or other displaced zone so as to reduce the quantity of fluid in contact with the rotary element and hence the transmitted torque. Means is also provided for varying the pumping action to modify the quantity of fluid in the casing.

Abstract: The invention provides a pneumatic control system for a pneumatically operated clutch in the drive to a cooling fan of a vehicle engine. There are two thermostat valves arranged in series in the pneumatic control line. One valve is positioned in the supercharged air passage and the other valve is in the liquid coolant passage. If the temperature at either valve becomes excessive the supply line 22 is connected to relief and the fan clutch automatically engages.